Anti-pollution system for solid fuel-fired steam generating power plants

ABSTRACT

An anti-pollution system for solid fuel-fired steam generating power plants which eliminates smokestacks. The system comprises a typical steam generator including a furnace having steam generating tubes along its walls, said furnace having one or more outlets for discharge of hot gaseous products of incomplete combustion therefrom including fly-ash and means for introducing ash-containing pulverized fuel and combustion air into a portion of said furnace remote from said outlet for combustion of said fuel, an ash pit below said furnace, an ash settling pond, means for flushing ash from said ash pit to said ash settling pond, and pump and conduit means connecting said outlet with said ash flushing means for passing said hot gaseous other products and combustion from said furnace outlet to said settling pond.

United States Patent Sahm [54] ANTI-POLLUTION SYSTEM FOR SOLID FUEL-FIRED STEAM GENERATING POWER PLANTS Inventor: E A-11,88 1 R-Pf lBQ Homer City, Pa. 15748 [22] Filed: June 15, 1971 [21] Appl.No.: 153,211

[451 Aug. 8, 1972 3,572,264 3/1971 Mercer ..l10/8 Primary Examiner-Kenneth W. Sprague Attorney-Larson, Taylor and Hinds [57] ABSTRACT An anti-pollution system for solid fuel-fired steam generating power plants which eliminates smokestacks. The system comprises a typical steam generator including a furnace having steam generating tubes along its walls, said furnace having one or more outlets for discharge of hot gaseous products of incomplete combustion therefrom including fly-ash and means for introducing ash-containing pulverized fuel and combustion air into a portion of said fumaceremote from said outlet for combustion of said fuel, an ash pit below said furnace, an ash settling pond, means for flushing ash from said ash pit to said ash settling pond, and pump and conduit means connecting said outlet with said ash flushing means for passing said hot gaseous other products and combustion from said furnace outlet to said settling pond.

7 Claims, 1 Drawing Figure PATENTED 8W? 3,682,139

INVENTOR PAUL A. B. SAHM ATTORNEYS ANTI-POLLUTION SYSTEM FOR SOLID FUEL- FIRED STEAM GENERATING POWER PLANTS This invention relates to an anti-pollution system for solid fuel fired power stations which eliminate smokestacks. V

Since fire was first tamed, the smoke went up, and it was assumed that that was where it belonged. However, it always came down again, somewhere, together with all the poisons it contained. Moreover, it is becoming increasingly apparent, both on a state and national level, that the present power supply is most inadequate for either summer or winter peak loads and will require doubling in the next decade. To meet this demand without putting smoke into the air and polluting the atmosphere has become one of the crises of our times.

It is an object of the invention to provide a steam generating power plant which eliminates expensive smokestacks together with the adverse public fears of smoke and other air pollutants.

Another object of the invention is not only to eliminate smokestacks but also to eliminate the need for the expensive electrical precipitation systems they contain.

These and other objects of the invention are achieved by an anti-pollution system for solid fuel power plants comprising a typical steam generator including a furnace having steam generating tubes along its walls,'said furnace having one or more outlets for discharge of hot gaseous other products of combustion therefrom and means for introducing ash-containing fuel and combustion air into a portion of the furnace remote from the outlet for combustion of the fuel. An ash pit is disposed below the ash pit and means are provided for flushing the ash to a settling pond. A pump and conduit means connects the outlet of the furnace with the ash flushing means and hot gaseous products of combustion from the furnace, rather than being directed to a chimney as is normally done, are passed by means of said pump and conduit means to said ash flushing means and, hence, to the settling pond.

If desired, there may be included in the pump and conduit means connecting the outlet of the furnace and the ash flushing means for more efiicient operation one or more additional pollutant extraction apparatus such as dust collectors or filters, electrostatic smoke particle precipitators, acid neutralizers, and the like.

The ashes of all inland systems are now sluiced to settling ponds through underground piping and the like conveying means. The present invention contemplates use of these same pipes for the stack effluents which will contribute only a small amount of solids. Since large cooling ponds are used for the ashes, the same source can be used for the firebox or furnace effluents.

It is appreciated that the prior art has disclosed a variety of special apparatus whereby smoke is passed through water to scrub away pollutants. All of these apparatus are not only very expensive to implement, but leave much to be desired from the standpoint of efficiency. The substantial economic advantages presented by the present invention are self-evident and need no elaboration. What is not as apparent, but nevertheless true, is the greater efficiency of the apparatus of the invention. It has been surprisingly found that diverting the entire effluent to ash disposal systems of power plants is a highly effective means for removing pollutants from the effluent apparently because of the absorption characteristics of the ash present.

The invention will be concisely set forth in the claims appended hereto; but for a more complete understanding of the invention, its advantages and uses, recourse should be had to the following description which refers to the accompanying drawing.

The single FIGURE of the drawing is a diagrammatic representation of a preferred embodiment of the apparatus of the invention.

Referring to the drawing, coal stored in a large pile 1 is fed into a breaker 3 where it is reduced in size and delivered by means of a conveyor 5 to a bunker 7 which pulverizes the coal usually into a powder so that the maximum amount of its energy may be transferred upon combustion. The pulverized coal is blown by a fan 9 into a steam generator indicated generally as 10, including a furnace ll lined with steam generating tubes 15 and fired by means of burners (not shown) disposed about the inside of the furnace. The coal is transferred into furnace l 1 by means of conduit 13, and preheated air coursing downwardly through tank conduit 17 is introduced into the furnace 11 via a plurality of nozzles 18 (only one of which is shown in the drawing) positioned so that the air emitted therefrom will blast in an upward and approximately tangential direction into the interior of the furnace. Although the pulverized coal may be introduced into the furnace separate of the preheated air, the two are most commonly introduced together. The upward and tangential direction of the nozzles is utilized to create an upwardly whirling motion to the pulverized coal and the resulting combustion gases which results in more efficient combustion and tends to assure equal and efficient contact between the combustion gases and steam generating tubes 15.

Adjacent the upper end of the furnace 11 is positioned a steam and water drum 20 which communicates by means of downcomer 19 with the upper ends of steam generating tubes 15 and by means of downcomer 21 with the lower end of the steam generating tubes 15. Through the circulating system thus formed, water from drum 17 flows downward through downcomer 21 and, by means of a circulating pump (not shown), is forced through steam generating tubes 15 and downcomer 19 back into drum 20. In passing through tubes 15, a portion of this water is converted into steam by the heat given up by the hot combustion gases with which they come into contact. The resulting steam and water mixture enters drum 20 and the components separated therein by means of a suitable mechanism (not shown) disposed therein.

In order to raise the temperature of this saturated steam, the steam generator is provided with a radiant superheater 25. Steam from the drum 20 is conveyed by means of a conduit 24 into the superheater 25 and from there by means of line 28 to steam turbine 27 where it delivers energy to the turbine. Exhaust steam from the turbine 27 is conveyed by line 30 to condenser 32 and from there by means of line 34 to line 36. A boiler feed pump 38 pumps condensed water from condenser 32 to an economizer 40 by line 36 and then via line 42 to drum 20.

All of the high temperature combustion gases, often at temperatures of 2,500-3,500 F and including smoke, fly ash, dirt, etc., exit trunk conduit at outlet 43 and enter conduit 44 by which they are directed to the ash disposal system as will be described in detail below.

, The bottom of the furnace is provided with an ash pit 46 for the collection of ashes from the furnace. A conduit 48 connects the ash pit 46 with ash conveying means 50 which may take the form, for instance, of a sluiceway, a pipe, or the like, that may constitute underground piping by which ashes from the furnace are sluiced to a settling pond. Water or other suitable flushing media (not shown) are passed into conduit 52 and the ash from ash pit 46 flushed with the aid of a pump 54 through the ash conveying means 50 into settling pond S6.

The hot combustion gases passing from the trunk conduit 17 into conduit 44, rather than being conveyed to a chimney or stack, are delivered by means of a conduit 44 to the ash conveying means 50 where they are flushed out with the ashes to the settling pond. During passage of the hot combustion gases from outlet 43 to ash conveying means 50, the gases are preferably sent through one or more additional pollutant extraction apparatus indicated diagrammatically as 56'. Any of the well known smoke byproduct removel equipment may be employed at this stage of the system as, for instance, filters, dust collectors, electrostatic precipitators, acid neutralizers, etc. A pump 58 is provided to assist in directing the combustion gases to ash conveying means 50 and, in combination with the action of pump 54, to settling pond 56. In the settling pond, the gases percolate through the water in the pond, and residual particles are removed and settle to the bottom. The pond sediment can be periodically removed and serves as a source of fly ash which has found utility in the manufacture of building blocks, and the like.

Although the invention has been described with reference to a particular boiler, it should be apparent that the invention is applicable to all boilers having solid-fuel burning furnaces or fireboxes that include an ash pit. In addition, the specific engineering arrangements of the components and equipment of the invention required for efficient operation will vary, depending upon the particular locality and the specific boiler and accessories employed.

It is claimed:

1. An anti-pollution system for solid fuel-fired steam generating power plants comprising a steam generator including a furnace having steam generating tubes along its walls, said furnace having an outlet for discharge of hot gaseous products of combustion therefrom and means for introducing ash-containing fuel and combustion air into a portion of said furnace remote from said outlet for combustion of said fuel, an ash pit below said furnace, an ash settling pond, means for flushing ash from said ash pit to said ash settling pond, and pump and conduit means connecting said outlet with said ash flushing means for passing said hot gaseous products of combustion from said furnace outlet to said settling pond.

2. The anti-pollution system of claim 1 wherein said ash flushing means comprises an ash flushing pump and an ash conveying means.

3. The anti-pollution system of claim 2 wherein the ash conveying means is an ash sluiceway.

4. The anti-pollution system of claim 2 wherein the ash conveying means is an conduit.

5. The anti-pollution system of claim 1 wherein the are u rsgrieasarrrs srtaaistairs: pollutant extraction means.

6. The anti-pollution extraction system of claim 5 wherein the additional pollutant extraction means is selected from dust collector means, and neutralizing means and smoke electrostatic particle precipitator means.

7. The anti-pollution extraction system of claim 6 wherein the steam generator includes a fuel fired furnace having upright steam generating tubes along at least the lower portions of its walls, a steam and water drum at the upper part of the steam generator receiving the steam generated in said wall tubes, contiguously arranged and horizontally disposed rediant superheater tubed, a gas confining enclosure leading from the upper part of the furnace, an economizer within said gas confining enclosure, conduit means connecting said economizer with said steam and water drum. 

1. An anti-pollution system for solid fuel-fired steam generating power plants comprising a steam generator including a furnace having steam generating tubes along its walls, said furnace having an outlet for discharge of hot gaseous products of combustion therefrom and means for introducing ash-containing fuel and combustion air into a portion of said furnace remote from said outlet for combustion of said fuel, an ash pit below said furnace, an ash settling pond, means for flushing ash from said ash pit to said ash settling pond, and pump and conduit means connecting said outlet with said ash flushing means for passing said hot gaseous products of combustion from said furnace outlet to said settling pond.
 2. The anti-pollution system of claim 1 wherein said ash flushing means comprises an ash flushing pump and an ash conveying means.
 3. The anti-pollution system of claim 2 wherein the ash conveying means is an ash sluiceway.
 4. The anti-pollution system of claim 2 wherein the ash conveying means is an conduit.
 5. The anti-pollution system of claim 1 wherein the pump and conduit means connecting said outlet with said ash flushing means includes at least one additional pollutant extraction means.
 6. The anti-pollution extraction system of claim 5 wherein the additional pollutant extraction means is selected from dust collector means, and neutralizing means and smoke electrostatic particle precipitator means.
 7. The anti-pollution extraction system of claim 6 wherein the steam generator includes a fuel fired furnace having upright steam generating tubes along at least the lower portions of its walls, a steam and water drum at the upper paRt of the steam generator receiving the steam generated in said wall tubes, contiguously arranged and horizontally disposed rediant superheater tubed, a gas confining enclosure leading from the upper part of the furnace, an economizer within said gas confining enclosure, conduit means connecting said economizer with said steam and water drum. 